The present invention relates to primary memory (also known as main memory) modules, and more particularly, to a primary memory module with a record of usage history.
A primary memory in a computer system is essentially provided for a processor (CPU) to store temporary programs and data currently being processed, and comes in two categories according to structure and functionality, namely, read-only memory (ROM) and random access memory (RAM). A secondary memory stores both processed and unprocessed programs and data, can get back the stored programs and data even when not powered, and usually features large capacity and permanent storage. Examples of the secondary memory include magnetic disk, magnetic tape, and compact disk.
The primary memory, such as DRAM, is typically manufactured by an integrated circuit process. Details of DRAM can be found, for example, in “Memory technology evolution: an overview of system memory technologies,” Technology brief 9th edition, published by Hewlett-Packard, which is incorporated herein by reference.
Although, theoretically speaking, DRAM is subject to no limit on the number of times it can be read and written, this is not true in practice. Like any other industrial product, a primary memory does not have an unlimited service life even when it is used appropriately. In general, as usage time passes, a primary memory module undergoes wear and tear and thereby ends up with various failures, for example, single bit errors and multiple bit errors. Conventionally, single bit errors can be detected and corrected according to the prior art, but multiple bit errors can be detected but not corrected. If the core code of the a data processing system executes from a memory region including a multiple bit error, the multiple bit error can cause the data processing system to hang.